1. Field of the Invention
The present invention generally relates to valve and, more particularly, to shock-absorbing one-way liquid flow control valves of an improved type.
2. Prior Art
One way liquid flow control valves of various types have been designed and utilized. Certain of such valves include flexible valve members. Those flexible valve members which are of relatively hard material, generally are not easy to open and are unsuitable for applications in which large pressure drops across the valve cannot be tolerated. Such hard valves also are usually very noisy to operate. However, when the flexible valve member is fabricated of a relatively soft material, it will usually readily deform so that only a very small pressure drop is necessary to open the valve. Unfortunately, very low temporary back pressure surges or increases also tend to close the valve, so that it is in many instances unsuitable for various applications.
Spring loaded check valves which rapidly close are commonly used in the plungers of electromagnetic fuel pumps employed in land vehicles and the like. Recently, electromagnetic pump plungers have been operated at relatively higher speeds than formerly. However, as pump plunger speeds increased and valve closing times correspondingly decrease, the pumps generate excessive noise. This noise is caused by shock waves generated by the valve in the plunger.
U.S. Pat. No. 3,797,522 seeks to address this problem. The patent describes a one-way valve which features knock dampening properties. However, the valve employs a valve element which utilizes a thin expandable elastic balloon or bulb, the expansion thereof having the effect of absorbing shock waves normally generated in the presence of back pressure in the valve. The balloon is necessarily fragile and subject to rapid wear in use due to the continuous overall expansion and contraction it undergoes and the fact it is made of organic easily damageable material. The valve itself is fabricated of rubber or the like, the expandable balloon also being of thin rubber or the like elastomer.
Accordingly, there remains a need for an efficient one-way liquid flow control valve for electromagnetic fuel pumps and the like, which valve is of durable construction and which effectively dampens or eliminates shock waves normally generated in the valve during periods of back pressure.